1.NSData和 base64 NSString的转换

1. NSString base64编码后的转NSData

  NSData *contentData = [[NSData alloc] initWithBase64EncodedString:content options:NSDataBase64DecodingIgnoreUnknownCharacters];

2.NSData转base64编码的字符串

NSData *encrptedData
[encrptedData base64EncodedStringWithOptions:NSDataBase64EncodingEndLineWithLineFeed];

2. NSData和NSString转换

1.NSString 转NSData

 NSData *contentData = [content dataUsingEncoding:NSUTF8StringEncoding];

2.NSData 转NSString

  NSString *con = [[NSString alloc] initWithData:encrptedData encoding:NSUTF8StringEncoding];

3.NSData和bytes的转换

1.NSData 转bytes

NSData *contentData
void const *initVectorBytes = contentData.bytes   //void const *表示可以指向任何类型的指针

2.bytes转NSData

 [NSData dataWithBytes:operationBytes length:actualOutSize]

4.NSString和bytes的转换

1.NSString转bytes

void const *initVectorBytes = [kInitVector UTF8String];

2.bytes转NSString

 NSString *data = [NSString stringWithCString:contentBytes encoding:NSUTF8StringEncoding];